1. Technical Field
The present invention relates to irradiation devices equipped with light sources that emit ultraviolet light or the like, and irradiation methods for irradiating ultraviolet light or the like using light sources that emit ultraviolet light or the like.
2. Related Art
Image formation apparatuses that arrange functional liquid on an image-formation target medium by discharging the functional liquid as droplets and cure the arranged functional liquid so as to form an image or the like have been known. It is carried out that light curing-type functional liquid is used to be arranged, and is cured by the irradiation of curing light to the arranged functional liquid as a method for controlling a curing timing and curing time of the functional liquid. Further, it is also carried out to irradiate property modification light to an image formation surface of an image-formation target medium so as to control an expansion manner of the functional liquid that has landed on the image-formation target medium, affinity of the functional liquid with the image-formation target medium, or the like. In order to carry out the irradiation of such curing light and property modification light in a stabilized manner, a light source that emits the above-mentioned light is required to exhibit its performance in a stabilized manner.
In JP-A-2005-125752, there is disclosed an ink jet recording apparatus that includes: a recording head for discharging a light curing ink which is cured by the irradiation of ultraviolet light onto a recording medium; a light irradiation device equipped with a light source which irradiates ultraviolet light to the discharged ink; a cooling device which cools the light irradiation device; a temperature detection unit which detects a temperature of the light irradiation device; and a control unit which carries out temperature control on the cooling device according to a detected temperature given by the temperature detection unit, and that forms an image while stabilizing light emission efficiency of a low-output ultraviolet light source.
In JP-A-2010-735, there are disclosed an ultraviolet curing-type ink jet printer and light source units used in the ultraviolet curing-type ink jet printer that can provide a method which prevents a light source unit from getting dirty due to ink mist floating over a print medium so as to stably maintain an appropriate irradiation efficiency with the configuration as follows. That is, in the UV curing-type printer, the light source units, which are respectively installed on the right and left sides sandwiching a print head, each include a light source whose output surface faces the print medium and that emits ultraviolet light toward the print medium, a fan that blows the outside air introduced from above to the light source for cooling it, and a guide structure that guides the cooling air. The guide structure guides the air which was blown by the fan and has cooled the light source so that it flows along the output surface of the light source in a direction being distanced from the side of the vicinity of the print head.
However, the ink jet recording apparatus disclosed in JP-A-2005-125752 is needed to install a temperature detection unit or the like, which raises a problem in that the ink jet recording apparatus becomes complicated and larger in size. In addition, it is not certain that the temperature of a portion related to light source characteristics of the light source can be appropriately measured without blocking a traveling path of the emitted light. Therefore, there has been a problem that appropriate control cannot necessarily be carried out.
In the ultraviolet curing-type ink jet printer and the light source units for the ultraviolet curing-type ink jet printer disclosed in JP-A-2010-735, since the guide structure and the like are not tailored to the characteristics of the light sources, there has been a problem in that cooling operation cannot necessarily be carried out in an appropriate manner in order to favorably maintain a function of the light source.